Sealed laminated electrical connector for helium filled disk drive

ABSTRACT

A novel disk drive includes a hermetically sealed helium-filled enclosure that has an opening extending through the disk drive base. A laminated electrical connector is disposed inside the enclosure, spans the opening, and is accessible from outside the disk drive base via the opening. The laminated electrical connector has an adhesive layer that is adhered to the disk drive base continuously around the opening, and that has a hole therethrough that is aligned with the opening. The laminated electrical connector includes electrically conductive traces that are electrically connected to the actuator flex cable, and a first insulative layer that is disposed on the trace layer. The laminated electrical connector has a metal foil sealing layer that continuously spans and completely covers the opening, and that has no holes therethrough that are aligned with the opening. The metal foil sealing layer overlaps the adhesive layer continuously around the opening.

FIELD OF THE INVENTION

The present invention relates generally to information storage devices,and in particular to hermetically sealed disk drive information storagedevices containing helium.

BACKGROUND

The typical hard disk drive includes a head disk assembly (HDA) and aprinted circuit board assembly (PCBA) attached to a disk drive base ofthe HDA. The HDA includes at least one disk (such as a magnetic disk,magneto-optical disk, or optical disk), a spindle motor for rotating thedisk, and a head stack assembly (HSA). The PCBA includes electronics andfirmware for controlling the rotation of the spindle motor and forcontrolling the position of the HSA, and for providing a data transferchannel between the disk drive and its host.

The spindle motor typically includes a rotor including one or more rotormagnets and a rotating hub on which disks are mounted and clamped, and astator. If more than one disk is mounted on the hub, the disks aretypically separated by spacer rings that are mounted on the hub betweenthe disks. Various coils of the stator are selectively energized to forman electromagnetic field that pulls/pushes on the rotor magnet(s),thereby rotating the hub. Rotation of the spindle motor hub results inrotation of the mounted disks.

The HSA typically includes an actuator, at least one head gimbalassembly (HGA), and a flex cable assembly. During operation of the diskdrive, the actuator must rotate to position the HGAs adjacent desiredinformation tracks on the disk. The actuator includes a pivot-bearingcartridge to facilitate such rotational positioning. The pivot-bearingcartridge fits into a bore in the body of the actuator. One or moreactuator arms extend from the actuator body. An actuator coil issupported by the actuator body, and is disposed opposite the actuatorarms. The actuator coil is configured to interact with one or more fixedmagnets in the HDA, to form a voice coil motor. The PCBA provides andcontrols an electrical current that passes through the actuator coil andresults in a torque being applied to the actuator.

Each HGA includes a head for reading and writing data from and to thedisk. In magnetic recording applications, the head typically includes aslider and a magnetic transducer that comprises a writer and a readelement. In optical recording applications, the head may include a minorand an objective lens for focusing laser light on to an adjacent disksurface. The slider is separated from the disk by a gas lubrication filmthat is typically referred to as an “air bearing.” The term “airbearing” is common because typically the lubricant gas is simply air.However, air bearing sliders have been designed for use in disk driveenclosures that contain helium, because an inert gas may not degradelubricants and protective carbon films as quickly as does oxygen. Heliummay also be used, for example, because it has higher thermalconductivity than air, and therefore may improve disk drive cooling.Also, because the air bearing thickness depends on the gas viscosity anddensity, the air bearing thickness may be advantageously reduced inhelium relative to air (all other conditions being the same).Furthermore, because helium has lower density than air, its flow (e.g.flow that is induced by disk rotation) may not buffet components withinthe disk drive as much, which may reduce track misregistration andthereby improve track following capability—facilitating higher datastorage densities.

Disk drive enclosures disclosed in the art to contain helium aretypically hermetically sealed to prevent an unacceptable rate of heliumleakage. Although some negligible amount of helium leakage isunavoidable, a non-negligible amount of helium leakage is undesirablebecause it can alter the thickness of the gas lubrication film betweenthe head and the disk, and thereby affect the performance of the head. Anon-negligible amount of helium leakage is also undesirable because itcan alter the tribochemistry of the head disk interface, possiblyleading to degradation in reliability, head crashes, and associated dataloss.

One challenge in the design and manufacture of disk drive enclosuresthat contain helium is to facilitate electrical communication betweenthe inside and outside of the disk drive enclosure while retaininghelium internal to the disk drive enclosure for sufficient time toensure adequate product reliability. Also, such electrical communicationmay be adversely affected by electromagnetic noise that may be receivedby the conductors across which such electrical communication takesplace. Thus, there is a need in the art for disk drive enclosure sealingmethods and structures that can facilitate electrical communicationbetween the interior and exterior of the disk drive, and that can retainhelium internal to a disk drive enclosure for a sufficient period oftime to ensure adequate post-manufacture product reliability andlifetime. There is also a need in the art for methods and structuresthat can improve shielding of such electrical communication fromelectromagnetic noise sources.

SUMMARY

A novel disk drive includes a hermetically sealed enclosure including adisk drive base and a top cover attached to the disk drive base. Theenclosure is helium-filled and has an opening extending through the diskdrive base. A spindle motor is attached to the disk drive base. A headactuator is disposed in the enclosure and includes a voice coil motor. Aflex cable is disposed in the enclosure and is attached to the headactuator. The flex cable is electrically connected to the voice coilmotor. A laminated electrical connector is disposed inside theenclosure. The laminated electrical connector spans the opening and isaccessible from outside the disk drive base via the opening. Thelaminated electrical connector has an adhesive layer adhered to the diskdrive base continuously around the opening. The adhesive layer has ahole therethrough that is aligned with the opening. The laminatedelectrical connector has a trace layer that includes electricallyconductive traces that are electrically connected to the flex cable, anda first insulative layer that is disposed on the trace layer. Thelaminated electrical connector has a metal foil sealing layer thatcontinuously spans and completely covers the opening. The metal foilsealing layer has no holes therethrough that are aligned with theopening. The metal foil sealing layer overlaps the adhesive layercontinuously around the opening. The trace layer and the firstinsulative layer are disposed between the metal foil sealing layer andthe adhesive layer. The laminated electrical connector also has astiffener layer, the metal foil sealing layer being disposed between thestiffener layer and the adhesive layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a disk drive according to the prior art.

FIG. 2 is a perspective view of a disk drive capable of including anembodiment of the present invention.

FIG. 3 is a top perspective view of a disk drive enclosure according toan embodiment of the present invention, with the top cover removed topermit viewing inside.

FIG. 4 is a bottom plan view of a disk drive according to an embodimentof the present invention.

FIG. 5 is an exploded perspective view of a laminated electricalconnector according to an embodiment of the present invention.

FIG. 6A is a perspective view of a laminated electrical connectoraccording to an embodiment of the present invention, before folding.

FIG. 6B is a perspective view of a laminated electrical connectoraccording to an embodiment of the present invention, during folding.

FIG. 6C is a perspective view of a laminated electrical connectoraccording to an embodiment of the present invention, after folding.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a plan view showing a schematic drawing of a magnetic diskdrive 50 according to the prior art. A disk drive base 52 together withan adjoining top cover (not shown to enable viewing of internalcomponents) forms a disk drive enclosure 54. Enclosed within the diskdrive enclosure 54 is a head gimbal assembly (HGA) 62 that includes aread/write head that can be loaded and unloaded from the surface of adisk 66 by the interaction between a load tang 70 and a ramp 64. Thedisk 66, also enclosed within the disk drive enclosure 54, is mounted ona spindle motor 68 that is attached to the disk drive base 52 and thatenables the disk 66 to rotate as indicated by arrow A. HGA 62 isattached to an actuator arm 56, for example by swaging at hole 63.Actuator arm 56 pertains to a head actuator 55, which is disposed in thedisk drive enclosure 54, and which pivots about pivot bearing cartridge58 in response to a torque from a voice coil motor 59. The torque iscreated by an electromagnet interaction between the voice coil motor 59and a static magnetic field provided by a permanent magnet assembly 60.

A circuit board (not shown) for controlling operation of the magneticdisk drive 50, and for enabling data communications between the magneticdisk drive 50 and an external host, is mounted on the bottom of the diskdrive base 52. The electrical path between the circuit board andread/write head of HGA 62 includes a flex cable 76 that is disposedwithin the disk drive enclosure 54. The flex cable 76 is attached to thehead actuator 55 and to a flex bracket 78. The flex bracket 78 ispositioned near an opening that extends through the disk drive base 52.The flex cable 76 is electrically connected to the voice coil motor 59,and may include a preamplifier 74.

FIG. 2 is a perspective view of a disk drive 80 capable of including anembodiment of the present invention. Disk drive 80 includes a disk driveenclosure that includes a disk drive base 82 and a top cover 84 attachedto the disk drive base 82 (by a plurality of screw fasteners in theembodiment of FIG. 2).

FIG. 3 is a top perspective view of the disk drive enclosure 300 of thedisk drive 80, according to an embodiment of the present invention. FIG.3 depicts the disk drive enclosure 300 of disk drive 80 with its topcover 82 removed, to permit viewing inside the disk drive enclosure 300.The disk drive enclosure 300 would otherwise be helium-filled (i.e.enclose a substantial concentration of helium gas) and hermeticallysealed. Also, FIG. 3 depicts the disk drive enclosure 300 with severalinternal components removed (e.g. disk, head actuator, flex cable, andpermanent magnets) to provide a less obstructed view of a novellaminated electrical connector 310 that is disposed inside the diskdrive enclosure 300.

Practically, the concentration of enclosed helium gas (e.g. versusremaining air) will be less than 100% initially, and is expected to dropover the useful life of the disk drive 100. Still, the disk drive 100may be considered “helium-filled” throughout its useful life so long asit continues to enclose a substantial concentration of helium gas. Notealso that 1.0 atmosphere pressure of helium is not required for the diskdrive 100 to be considered “helium-filled.” For example, thehelium-filled disk drive enclosure preferably initially encloses heliumhaving between 0.3 to 1.0 atmosphere partial pressure, and may alsoenclose air having between 0 to 0.7 atmosphere partial pressure. Incertain applications, it may be desirable for at least 70% of the heliumgas that is initially enclosed to remain enclosed after a 10 year usefullife of the hermetically sealed disk drive.

FIG. 4 is a bottom plan view of the disk drive 80. Now referringadditionally to FIG. 4, from the underside of disk drive 80 an opening400 can be seen. The opening 400 extends through the disk drive base 82to the disk drive enclosure 300. The laminated electrical connector 310spans the opening 400 and is accessible from outside the disk drive base82 from underneath via the opening 400.

FIG. 5 is an exploded perspective view of a laminated electricalconnector 310 according to an embodiment of the present invention. Nowreferring additionally to FIG. 5, the laminated electrical connector 310includes a first adhesive layer 511 adhered to the disk drive base 82continuously around the opening 400. For example, the first adhesivelayer 511 may be a layer of thermal set epoxy adhesive or acrylicadhesive, and may define an adhesive layer thickness in the range 25 to50 microns. The laminated electrical connector 310 also includes anadhesive tail 510 adhered to the disk drive base 82.

In the embodiment of FIG. 5, the first adhesive layer 511 has a hole 512therethrough that is aligned with the opening 400, so that the laminatedconnector 310 can be accessed from underneath and outside the disk drive80 (via the opening 400 and the hole 512). In this context, “alignedwith” merely means that the hole 512 and the opening 400 overlapsufficiently to allow access to one or more further layers (describednext) of the laminated connector 310 via the hole 512 and the opening400.

Also in the embodiment of FIG. 5, the laminated electrical connector 310includes a trace layer 530 that includes a plurality of electricallyconductive traces 532. The plurality of electrically conductive traces532 includes traces that are electrically connected to a flex cable(e.g. flex cable 76) internal to the disk drive enclosure 300. Forexample, the trace layer 530 may comprise a copper foil that isapproximately 12 microns thick. Also in the embodiment of FIG. 5, thelaminated electrical connector 310 includes a first insulative layer 540disposed on the trace layer 530. For example, the first insulative layer540 may be a polyimide layer having a thickness in the range 10 to 50microns. Optionally, the first insulative layer 540 may also include itsown adhesive layer in addition to such a polyimide layer.

The laminated electrical connector 310 also includes a metal foilsealing layer 550 (e.g. copper foil, aluminum foil, stainless steelfoil, etc) that continuously spans and completely covers the opening400. Preferably, the metal foil sealing layer 550 defines a metal foilthickness in the range 12 to 50 microns, which may advantageously reducethe likelihood of small pores or defects aligning or extending throughthe metal foil sealing layer 550. Note that the metal foil sealing layer550 has no holes therethrough that are aligned with the opening 400.Also, the metal foil sealing layer 550 overlaps the first adhesive layer511 continuously around the opening 400. FIG. 5 also shows that thetrace layer 530 and the first insulative layer 540 are disposed betweenthe metal foil sealing layer 550 and the first adhesive layer 511.

The metal foil sealing layer 550 described above may advantageouslyreduce the diffusion of helium through the laminated electricalconnector 310, both vertically by blocking diffusion in that direction,and horizontally by constraining the horizontal diffusion (e.g.laterally through the first insulative layer 540 and/or the firstadhesive layer 511) to occur through a path having a narrow aspect ratio(horizontal path length relative to path height).

Optionally, the laminated electrical connector 310 may also include asecond insulative layer 520 that is disposed between the trace layer 530and the first adhesive layer 511 (as shown in the embodiment of FIG. 5).In that case, the trace layer 530 is affixed to the disk drive base 82via the second insulative layer 520 (and the first adhesive layer 511and the adhesive tail 510). For example, the second insulative layer 520may comprise a polyimide layer having a thickness in the range 10 to 50microns. Alternatively the second insulative layer 520 may comprise asolder resist layer that is silk screened onto a second metal foil, withthe second insulative layer 520 oriented so that the second metal foilfaces the first adhesive layer 511. Such a second metal foil, regardlessof the composition of the second insulative layer 520, could enhanceelectromagnetic shielding and advantageously increase the length of thegas diffusion path, especially after the laminated electrical connector310 is folded (as described later herein).

In the embodiment of FIG. 5, the second insulative layer 520 includeswindows 522 and 524. Windows 522 permit access to the plurality ofelectrically conductive traces 532 of the trace layer 530 through thesecond insulative layer 520, from beneath and outside the disk drive 80via opening 400. Windows 524 permit the plurality of electricallyconductive traces 532 of the trace layer 530 to be accessed through thesecond insulative layer 520, from above and within the disk driveenclosure 300—after the laminated electrical connector 310 is folded ina way that is similar to the folding of the laminated electricalconnector 600 shown in FIGS. 6A, 6B, 6C and described later herein.

In the embodiment of FIG. 5, the laminated electrical connector 310 alsoincludes a stiffener layer 580. Preferably but not necessarily, thestiffener layer 580 may be a metal stiffener layer. In certainembodiments, the laminated electrical connector 310 may also include athird insulative layer 560 disposed between the metal foil sealing layer550 and the stiffener layer 580. The stiffener layer 580 may befabricated from stainless steel, aluminum, or plastic, for example.Optionally, the stiffener layer 580 defines a stiffener layer thicknessin the range 0.25 to 3 mm. Such a stiffener layer may provide mechanicalstiffness to the laminated electrical connector 310. Note that, in theembodiment of FIG. 5, the metal foil sealing layer 550 is disposedbetween the stiffener layer 580 and the first adhesive layer 511.Optionally, a second adhesive layer 570 may be disposed between thestiffener layer 580 and the metal foil sealing layer 550, as shown inthe embodiment of FIG. 5. For example, the second adhesive layer 570 maybe a layer of thermal set epoxy adhesive having a thickness in the range25 to 50 microns.

In the embodiment of FIG. 5, the plurality of electrically conductivetraces 532 preferably includes a second subset of electricallyconductive traces 534 that extends to and connects to a plurality ofelectrical terminals of the spindle motor (e.g. spindle motor 68). Thissecond subset of electrically conductive traces is seen in FIG. 5 toextend over the adhesive tail 510. Also in the embodiment of FIG. 5, themetal foil sealing layer 550 optionally extends along and completelycovers the second subset of electrically conductive traces 534. This mayprovide an advantageous additional electromagnetic shielding of thesecond subset of electrically conductive traces 534.

FIG. 6A is a perspective view of a laminated electrical connector 600according to an embodiment of the present invention, before folding. Thelaminated electrical connector 600 includes a middle portion 610 and twowing portions 612, 614, though optionally a single wing portion could beused. The laminated electrical connector 600 also preferably includes atail portion 616. Preferably but not necessarily, the laminatedelectrical connector 600 includes a plurality of notches 601, 602, 603,and 604.

FIG. 6B is a perspective view of the laminated electrical connector 600,during folding. Now referring additionally to FIG. 6B, the wing portions612, 614 are preferably folded along creases that are approximatelyaligned with the notches 601, 602, 603, and 604. In the view of FIG. 6B,a window 624 in the second insulative layer of the laminated electricalconnector 600 permits viewing of a portion of the surfaces of itsplurality of electrically conductive traces 632. FIG. 6C is aperspective view of the laminated electrical connector 600, afterfolding. Folding the laminated electrical connector 600 in this way maypermit a portion of its plurality of electrically conductive traces 632to be accessible from the top, via windows 624 in the second insulativelayer of the laminated electrical connector 600.

In the foregoing specification, the invention is described withreference to specific exemplary embodiments, but those skilled in theart will recognize that the invention is not limited to those. It iscontemplated that various features and aspects of the invention may beused individually or jointly and possibly in a different environment orapplication. The specification and drawings are, accordingly, to beregarded as illustrative and exemplary rather than restrictive.“Comprising,” “including,” and “having,” are intended to be open-endedterms.

1. A disk drive comprising: a hermetically sealed enclosure including adisk drive base and a top cover attached to the disk drive base, theenclosure being helium-filled and having an opening extending throughthe disk drive base; a spindle motor attached to the disk drive base; ahead actuator disposed in the enclosure and including a voice coilmotor; a flex cable being disposed in the enclosure and being attachedto the head actuator, the flex cable being electrically connected to thevoice coil motor; and a laminated electrical connector disposed insidethe enclosure, the laminated electrical connector spanning the openingand being accessible from outside the disk drive base via the opening,the laminated electrical connector comprising a plurality of layers, theplurality of layers including an adhesive layer adhered to the diskdrive base continuously around the opening, the adhesive layer having ahole therethrough that is aligned with the opening; a trace layer thatincludes a plurality of electrically conductive traces including a firstsubset electrically conductive traces that are electrically connected tothe flex cable; a first insulative layer disposed on the trace layer; ametal foil sealing layer that continuously spans and completely coversthe opening, the metal foil sealing layer having no holes therethroughthat are aligned with the opening, the metal foil sealing layeroverlapping the adhesive layer continuously around the opening, thetrace layer and the first insulative layer being disposed between themetal foil sealing layer and the adhesive layer; and a stiffener layer,the metal foil sealing layer being disposed between the stiffener layerand the adhesive layer.
 2. The disk drive of claim 1 further comprisinga second insulative layer that is disposed between the trace layer andthe adhesive layer, and wherein the trace layer is affixed to the diskdrive base via the second insulative layer.
 3. The disk drive of claim 1wherein the stiffener layer is a metal stiffener layer.
 4. The diskdrive of claim 1, wherein in the spindle motor includes a plurality ofelectrical terminals, and wherein the plurality of electricallyconductive traces includes a second subset of electrically conductivetraces that extends to and connects to the plurality of electricalterminals.
 5. The disk drive of claim 4 wherein the metal foil sealinglayer extends to the plurality of electrical terminals and completelycovers the second subset of electrically conductive traces.
 6. The diskdrive of claim 1 wherein the metal foil sealing layer comprises copperfoil.
 7. The disk drive of claim 1 wherein the adhesive layer defines anadhesive layer thickness in the range 25 to 50 microns.
 8. The diskdrive of claim 1 wherein the metal foil sealing layer defines a metalfoil thickness in the range 12 to 50 microns.
 9. The disk drive of claim1 wherein the stiffener layer defines a stiffener layer thickness in therange 0.25 to 3 mm.
 10. The disk drive of claim 1 wherein the firstinsulative layer comprises polyimide having a thickness in the range 10to 50 microns.
 11. The disk drive of claim 1 wherein the adhesive layercomprises an epoxy adhesive.
 12. The disk drive of claim 1 wherein thelaminated electrical connector includes a middle portion and at leastone wing portion, and wherein the wing portion is folded over the middleportion.
 13. The disk drive of claim 2 wherein the second insulativelayer includes a second metal foil that faces the adhesive layer. 14.The disk drive of claim 2 wherein the laminated electrical connectorincludes a middle portion and at least one wing portion, and wherein thewing portion is folded over the middle portion.
 15. The disk drive ofclaim 14 wherein the second insulative layer includes at least onewindow therethrough and over a portion of the trace layer.
 16. The diskdrive of claim 3 further comprising a third insulative layer disposedbetween the metal foil sealing layer and the metal stiffener layer.